1. Field of the Invention
The present invention relates to a cleaning device and an image forming apparatus, and more particularly to a cleaning mechanism for a belt for use in the transfer process of image formation.
2. Discussion of the Background
In an image forming apparatus, for example, a multifunction printer, a photocopier, a facsimile machine, a printer or a printing machine, a latent electrostatic image formed on a photoreceptor functioning as an image bearing member is visualized by toner. Then, the visualized image is transferred to a recording medium, for example, a sheet form recording medium (e.g., transparent sheet) and fixed by a fixing device to produce a copier or print output.
Images formed on a photoreceptor are not only monochrome images but also full color images. In the transfer process in which full color images are formed, there is a structure in which each color image is sequentially transferred in a process of moving a recording medium through the image forming portion having multiple photoreceptors arranged side by side. In addition thereto, for example, published unexamined Japanese patent application No. (hereinafter referred to as JOP) 2006-078679 describes a structure in which a primary image transfer is performed using an intermediate body, for example, a belt, and the obtained resultant overlapped image is secondarily transferred at one time to a recording medium.
Cleaning of the intermediate transfer body is performed to remove remaining toner and/or paper dust after the transfer of the overlapped image to the recording medium at one time. With regard to the structure for the cleaning, for example, JOP 2001-318541 describes a structure having a blade and a brush roller which is brought into contact with an intermediate transfer body.
As described in JOP 2001-318541, it is well known that toner and paper dust remaining on a belt functioning as an intermediate transfer body tend to be attached at the ends in the breadth direction of the belt. Thus, with regard to the cleaning of an intermediate transfer body, there can be used a structure having at least a cleaning member at the ends located in the breadth direction of the belt or a belt form cleaning member moving along the breadth direction to scrape toner and/or paper dust attached to the surface of the belt near its ends. However, when toner and paper dust attached to the surface of a belt near its ends are removed, the following problems may arise.
FIG. 10 represents a structure having a belt A functioning as an intermediate transfer body, a cleaning blade B and a cleaning brush C. The cleaning blade B and the cleaning brush C are brought into contact with the belt A such that all the area in the breadth direction of the belt A is covered. In this structure, the cleaning blade B banks up or the cleaning brush C scrapes toner T remaining on the belt covering the image formation area on the intermediate transfer belt. Banks up means that toner accumulates in a mound, pile, or ridge. However, when the toner T banked up by the blade is accumulated, the toner T may be pushed to the ends in the breadth direction of the blade B. As a result, the toner may be brimmed over or slipped from the ends of the cleaning blade A or the cleaning brush B as indicated by the arrows illustrated in FIG. 10.
The toner slipped from or brimmed over the end of such a cleaning device scatters around and tends to contaminate or abrade peripherally arranged devices. Furthermore, the toner still remaining on and attached to the belt easily forms toner filming on the belt surface. This may lead to deterioration of charging characteristics of an intermediate transfer body and damage to the cleaning device.
Another collecting member (D represented in FIG. 10) or a sealing member dedicated to cover the end of the belt may be provided. However, it is difficult to completely prevent the toner from slipping from the end of the collecting member. When an air-tight sealing member is provided, the internal pressure thereof may abnormally increase and blow up. Thus, another member may be provided to prevent these problems and it is inevitable to make the structure complicated.